Atomic Bonding and Structure

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Atoms

Mass Number

-Total number of Protons and Neutrons

Atomic Number

-Number of Protons

Number of Protons=Number of Electrons

Compounds

Chemically bonded

Through a chemical reaction

Hard to Separate

More than one element

Isotopes

Different atomic forms of the sane element

Have the same number of protons

But a different number of neutrons

They have the same atomic number

But a different mass number

Ionic Bonding

Atoms loose or gain electrons

All atoms want to be stable (full outer shell)

Non metal and a metal

Become positive if they lose an electron

Become native if they gain one

Are now attracted

Structure

Ionic compounds always have giant ionic lattices

Regular lattice arrangement

Held together by strong electrostatic forces

between oppositely charged electrons

Properties

High melting/boiling points - because of strong forces between- need lots of energy to break

conduct electricity when melted- electrons are free to move

Dissolve in water easily-can carry an electric current

Ions

If an atom is an ion if it has...

lost or gained electrons

has the structure of a noble gas

the charge is the same as the group number (only for positive)

Any positive ions that combine with negative ions form a ionic compound

Formula

Ionic compounds are made up of the positively charged and the negatively charged parts

The overall charge will always be 0

charges must always balance to 0

Covalent Bonds

Atoms sharing electrons

Only share outer electrons only

Want to have a full shell-be stable

A covalent bond is a pair of Shared electrons

Share electrons to create a full outer shell

Structure

Simple Molecular Substances

OR

Giant covalent Structure

Simple Molecular Substances

Small molecules

Strong bonds

weak forces of attraction between intermolecular forces

means low melting/boiling point

most are liquids or solids

Don't conduct electricity- no ions, no electrical charge

Giant Covalent Structures

Similar to giant ionic structures (lattices)

No charged electrons

Bonded with strong covalent bonds

High boiling/melting points

Examples of Giant Covalent Structures

Diamond

Each carbon has 4 covalent bonds

Very ridged structure

Makes it extremely hard

Graphite

Each carbon forms three covalent bonds

Layers that can slide over each other

makes it soft and slippery

Layers are lose

Because of weak intermolecular forces

conducts electricity an heat

because ach carbon has a delocalised electron

Silicon Dioxide (Silica)

What sand is made of

Each grain of sand is one giant structure

Of silicon and oxygen

Metallic Structures

Metals have a giant structure

Metallic bonds have 'free electrons'

Delocalised electrons come from the outer shell

Free to move

Reason why they are good conductors of heat and electricity

Electrons hold atoms together in regular structure

This is because of electrostatic attraction between positive metal ions and negative electrons

Layers slide over each other

They can be bent and shaped

Alloys

Harder than pure metal

Different elements have different sized atoms

When metals are mixed the structure is distorted

The layers can no longer slide over each other as easily

Atoms, Compunds and Isotopes

Ionic Bonding

Ions

Covalent Bonding

Metallic Structures